Control devices such as controllers, Intelligent Electronic Devices, etc., are used in industries to monitor and control various equipment. Additionally, the control devices also perform the function of logging faults which occur in an automation environment. Along with the faults, the control devices also log the respective time instances of the corresponding faults. The order of faults logged by the control devices can be identified from the respective time instances logged by the control devices. In order to design better protection systems for the automation environment, it is essential that the correct sequence of the faults is identified. Therefore it is critical for the plurality of control devices to be time synchronized.
In order to achieve time synchronization, high end control devices have advanced time synchronization capabilities through various protocols. The use of such various protocols requires time stamping at network interface hardware corresponding to each of a plurality of communicating elements, a master clock and a plurality of network elements with boundary clocks.
Equipment required for such precision time synchronization, over a communication network, are relatively expensive. Such equipment are not cost effective for low end control devices. Therefore time synchronization of the low end control devices is done manually, by plugging the device to a standalone PC or a handheld device, usually through a serial interface. The method of time synchronization involves manually writing a reference time to the control device's clock. This is time consuming and inefficient method, especially when large number of control devices are distributed over a large area inside the plant. Moreover the method is not accurate and the time synchronization errors may vary from several milliseconds to a few seconds.
Therefore there is a need for an improvised method for time synchronization of control devices in the automation environment.